It is known from prior art that thin webs and films can be made from microfibrillated cellulose (MFC). The term thin film is meant to define a film having a basis weight of less than 30 g/m2. This can be accomplished by either applying MFC on a plastic substrate or by applying fibers on a wire and using vacuum suction for very long time.
At high production speeds, normally pulsating dewatering elements are used on the wire section (such as register rolls, foils, vacuum foils etc). These pulsating dewatering elements open up the formed wet web structure and allow faster dewatering—leading to higher production rate. However, this also has a negative effect on the oxygen barrier properties of the produced films and may cause pin-holes in the film.
There is thus a need for a way of manufacturing a thin MFC film on a paper or board making machine at high speeds, which film shows high oxygen barrier properties and to avoid problems with pin-holes connected with prior art solutions.